1. Field of the Invention
The present invention relates to a method and apparatus for flushing the filter membrane of a reverse osmosis water purification system.
2. Description of Related Art
Reverse osmosis (RO) water purification systems contain an osmotic membrane that removes impurities from water. The purified water is typically stored in a tank for subsequent removal by the user. The filter membrane is usually housed within a filter unit that has an inlet port, and outlet port and a drain. The drain removes the excess water that does not flow through the membrane. The outlet port is coupled to the tank. The inlet port is connected to a municipal water line, typically through one or more prefilters.
The municipal water pressure is typically sufficient to push the water through the membrane. For filter sites that have relatively low water pressure, the RO system may include a pump which pumps the water through the osmotic membrane. The pump is typically coupled to level sensors within the tank that activate and deactivate the pump when the water level within the tank reaches predetermined lower and upper levels, respectively.
To extend the use of an RO system, the osmotic membrane is periodically flushed to remove the impurities from the surface of the membrane. Some systems utilize the pump to direct water into the outlet port of the filter unit and back into the drain. Systems with bladder pressurized accumulators may utilize the pressure of the bladder to direct water back through the filter system. Flushing the membrane with a pump or bladder increases the complexity of the system. Additionally, some systems do not have a pump or bladder to pump the flush water, therefore such systems are not capable of flushing the membrane. It would be desirable to have an RO system that can flush the osmotic membrane without requiring the use of a pump or other similar pumping device.